Investigation of slip/no-slip surface for two-dimensional large tilting pad thrust bearing

2017 ◽  
Vol 69 (6) ◽  
pp. 995-1004 ◽  
Author(s):  
Zhixiang Song ◽  
Fei Guo ◽  
Ying Liu ◽  
Songtao Hu ◽  
Xiangfeng Liu ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Slip Surface ◽  
Load Capacity ◽  
Slip Condition ◽  
Optimized Design ◽  
Two Dimensional ◽  
Boundary Slip ◽  
Content Type ◽  
Tilting Pad ◽  
Turbulence Effect

Purpose This paper aims to present the slip/no-slip design in two-dimensional water-lubricated tilting pad thrust bearings (TPTBs) considering the turbulence effect and shifting of pressure centers. Design/methodology/approach A numerical model is established to analyze the slip condition and the effect of turbulence according to a Reynolds number defined in terms of the slip condition. Simulations are carried out for eccentrically and centrally pivoted bearings and the influence of different slip parameters is discussed. Findings A considerable enhancement in load capacity, as well as a reduction in friction, can be achieved by heterogeneous slip/no-slip surface designs for lubricated sliding contacts, especially for near parallel pad configurations. The optimized design largely depends on the pivot position. The load capacity increases by 174 per cent for eccentrically pivoted bearings and 159 per cent for centrally pivoted bearings for a suitable design. When slip zone locates at the middle of the radial direction or close to the inner edge, the performance of the TPTB is better. Research limitations/implications The simplification of slip effect on the turbulence (definition of Reynolds number) can only describe the trend of the increasing turbulence due to slip condition. The accurate turbulence expression considering the boundary slip needs further explorations. Originality/value The shifting of pressure center due to the slip/no-slip design for TPTBs is investigated in this study. The turbulence effect and influence of slip parameters is discussed for large water-lubricated bearings.

Effect of non-Newtonian magneto-elastohydrodynamic on performance characteristics of slider-bearings

2019 ◽  
Vol 71 (10) ◽  
pp. 1158-1165
Author(s):  
Mouhcine Mouda ◽  
Mohamed Nabhani ◽  
Mohamed El Khlifi
Keyword(s):  
Friction Coefficient ◽  
Design Methodology ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Transverse Magnetic ◽  
Finite Width ◽  
Two Dimensional ◽  
Content Type ◽  
Slider Bearings ◽  
First Time

Purpose This study aims to examine the magneto-elastohydrodynamic effect on finite-width slider-bearings lubrication using a non-Newtonian lubricant. Design/methodology/approach Based on the magneto-hydrodynamic (MHD) theory and Stokes micro-continuum mechanics, the modified two-dimensional Reynolds equation including bearing deformation was derived. Findings It is found that the bearing deformation diminishes the load-capacity and increases the friction coefficient in comparison with the rigid case. However, the non-Newtonian effect increases load-capacity but decreases the friction coefficient. Moreover, the use of a transverse magnetic field increases both the friction coefficient and load capacity. Originality/value This study combines for the first time MHD and elastic deformation effects on finite-width slider-bearings using a non-Newtonian lubricant.

A series solution of the boundary value problem arising in the application of fluid mechanics

2018 ◽  
Vol 28 (10) ◽  
pp. 2480-2490 ◽  
Author(s):  
Yasir Khan
Keyword(s):  
Differential Equation ◽  
Reynolds Number ◽  
Transverse Direction ◽  
Hydrodynamic Flow ◽  
Porous Channel ◽  
Second Grade ◽  
Two Dimensional ◽  
Second Grade Fluid ◽  
Content Type ◽  
Grade Fluid

Purpose This paper aims to study the two-dimensional steady magneto-hydrodynamic flow of a second-grade fluid in a porous channel using the homotopy perturbation method (HPM). Design/methodology/approach The governing Navier–Stokes equations of the flow are reduced to a third-order nonlinear ordinary differential equation by a suitable similarity transformation. Analytic solution of the resulting differential equation is obtained using the HPM. Mathematica software is used to visualize the flow behavior. The effects of the various parameters on velocity field are analyzed through appropriate graphs. Findings It is found that x component of the velocity increases with the increase of the Hartman number when the transverse direction variable ranges from 0 to 0.2 and the reverse behavior is observed when transverse direction variable takes values between 0.2 and 0.5. It is noted that the y component of the velocity increases rapidly with the increase of the transverse direction variable. The y component of the velocity increases marginally with the increase of the Hartman number M. The effect of the Reynolds number R on the x and y components of the velocity is quite opposite to the effect of the Hartman number on the x and y components of the velocity and the effect of the parameter on the x and y components of the velocity is similar to that of the Reynolds number. Originality/value To the best of the author’s knowledge, nobody had tried before two-dimensional steady magneto-hydrodynamic flow of a second-grade fluid in a porous channel using the HPM.

Optimal design of the slip–texture on a journal-bearing surface

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jian Jin ◽  
Xiaochao Chen ◽  
Yiyang Fu ◽  
Yinhui Chang
Keyword(s):  
Journal Bearing ◽  
Slip Surface ◽  
Interfacial Shear Stress ◽  
Journal Bearings ◽  
Combined Effects ◽  
Boundary Slip ◽  
Programming Technique ◽  
Content Type ◽  
Slip Regime ◽  
Lubrication Performance

Purpose This work aims to explore the combined effects of boundary slip and texturing on hydrodynamic journal bearings and identifies optimized slip and texture patterns to improve the performance of journal bearings. Design/methodology/approach The quadratic programming technique is used to study the influence of boundary slip on the lubrication performance of a two-dimensional journal bearing. A numerical model is used to analyze the effect of the cylindrical texture shape on the characteristics of journal bearings. It is concluded that the combination of slip and texture can be an effective approach to improve the performance of hydrodynamic journal bearings. Findings The results show that there is an interfacial shear stress (perfect slip surface) and that the role of the slip regime is to reduce friction. Numerical analyses indicate that the location and size of the slip and texture zone have a large effect on journal bearings. A comparison of the distribution forms of various texture–slip combinations indicates that the full texture–slip combination can prominently reduce the load-carrying capacity and that the “forward-slip backward-texture” configuration can considerably improve the performance of journal bearings. Originality/value The combined effects of boundary slip and texture on hydrodynamic journal bearings are meticulously examined. The patterns of the slip and texture are optimized, which can substantially improve the journal bearing performance.

Effect of slip position on the hydrodynamic performance of liquid film seal

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yun-lei Wang ◽  
Jiu-hui Wu ◽  
Zhen-tao Li ◽  
Lu-shuai Xu
Keyword(s):  
Mathematical Model ◽  
Liquid Film ◽  
Peer Review ◽  
Slip Surface ◽  
Design Method ◽  
Hydrodynamic Performance ◽  
Boundary Slip ◽  
Content Type ◽  
Navier Slip ◽  
Sealing Performance

Purpose The purpose of this paper is to investigate the effect of slip position on the performance of liquid film seal. Design/methodology/approach A mathematical model of liquid film seal with slip/no-slip surface was established based on the Navier slip model and JFO boundary condition. Liquid film governing equation was discretized by the finite difference method and solved by the SOR relaxation iterative algorithm and the effects of slip position on sealing performance are discussed. Findings The results indicate that boundary slip plays an important role in the overall performance of a seal and a reasonable arrangement of slip position can improve the steady-state performance of liquid film seal. Originality/value Based on the mathematical model, the optimal parameters for liquid film seal with boundary slip at groove are obtained. The results presented in this study are expected to provide a theoretical basis to improve the design method of liquid film seal. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2020-0082/

Improved hydrodynamic performance of liquid film seal by considering boundary slip and cavitation

2019 ◽  
Vol 71 (9) ◽  
pp. 1108-1115 ◽  
Author(s):  
Yun-Lei Wang ◽  
Jiu-Hui Wu ◽  
Mu-Ming Hao ◽  
Lu-Shuai Xu
Keyword(s):  
Liquid Film ◽  
High Speed ◽  
Slip Surface ◽  
Slip Length ◽  
Design Method ◽  
Hydrodynamic Performance ◽  
Performance Parameters ◽  
Boundary Slip ◽  
Content Type ◽  
Navier Slip

Purpose The purpose of this paper is to investigate the effect of boundary slip on hydrodynamic performance of liquid film seal considering cavitation. Design/methodology/approach A mathematical model of liquid film seal with slip surface was established based on the Navier slip model and Jakobsson–Floberg–Olsson (JFO) boundary condition. Liquid film governing equation was discretized by the finite difference method and solved by the SOR relaxation iterative algorithm and the hydrodynamic performance parameters of liquid film seal were obtained considering boundary slip and cavitation. Findings The results indicate that the values of performance parameters are affected significantly by the slip length under the condition of high speed and low differential pressure. Originality/value The performances of liquid film seal are investigated considering slip surface and cavitation. The results presented in the study are expected to provide a theoretical basis to improve the design method of liquid film seal.

scholarly journals Improvement of Tilting-Pad Journal Bearing Operating Characteristics by Application of Eddy Grooves

Lubricants ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 18
Author(s):  
Eckhard Schüler ◽  
Olaf Berner
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Load Capacity ◽  
Fluid Film ◽  
Operating Characteristics ◽  
Fluid Film Bearings ◽  
Tilting Pad ◽  
Bearing Load ◽  
Bearing Loads ◽  
Tilting Pad Journal Bearing

In high speed, high load fluid-film bearings, the laminar-turbulent flow transition can lead to a considerable reduction of the maximum bearing temperatures, due to a homogenization of the fluid-film temperature in radial direction. Since this phenomenon only occurs significantly in large bearings or at very high sliding speeds, means to achieve the effect at lower speeds have been investigated in the past. This paper shows an experimental investigation of this effect and how it can be used for smaller bearings by optimized eddy grooves, machined into the bearing surface. The investigations were carried out on a Miba journal bearing test rig with Ø120 mm shaft diameter at speeds between 50 m/s–110 m/s and at specific bearing loads up to 4.0 MPa. To investigate the potential of this technology, additional temperature probes were installed at the crucial position directly in the sliding surface of an up-to-date tilting pad journal bearing. The results show that the achieved surface temperature reduction with the optimized eddy grooves is significant and represents a considerable enhancement of bearing load capacity. This increase in performance opens new options for the design of bearings and related turbomachinery applications.

Heat transfer enhancement using second mode self-oscillating structures

2019 ◽  
Vol 30 (7) ◽  
pp. 3827-3842
Author(s):  
Samer Ali ◽  
Zein Alabidin Shami ◽  
Ali Badran ◽  
Charbel Habchi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Flow Regime ◽  
Vortex Generator ◽  
Reynolds Numbers ◽  
Content Type ◽  
Laminar Flow Regime ◽  
Second Mode

Purpose In this paper, self-sustained second mode oscillations of flexible vortex generator (FVG) are produced to enhance the heat transfer in two-dimensional laminar flow regime. The purpose of this study is to determine the critical Reynolds number at which FVG becomes more efficient than rigid vortex generators (RVGs). Design/methodology/approach Ten cases were studied with different Reynolds numbers varying from 200 to 2,000. The Nusselt number and friction coefficients of the FVG cases are compared to those of RVG and empty channel at the same Reynolds numbers. Findings For Reynolds numbers higher than 800, the FVG oscillates in the second mode causing a significant increase in the velocity gradients generating unsteady coherent flow structures. The highest performance was obtained at the maximum Reynolds number for which the global Nusselt number is improved by 35.3 and 41.4 per cent with respect to empty channel and rigid configuration, respectively. Moreover, the thermal enhancement factor corresponding to FVG is 72 per cent higher than that of RVG. Practical implications The results obtained here can help in the design of novel multifunctional heat exchangers/reactors by using flexible tabs and inserts instead of rigid ones. Originality/value The originality of this paper is the use of second mode oscillations of FVG to enhance heat transfer in laminar flow regime.

Effects of Heat Transfer During Peristaltic Transport in Nonuniform Channel With Permeable Walls

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Siddharth Shankar Bhatt ◽  
Amit Medhavi ◽  
R. S. Gupta ◽  
U. P. Singh
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Incompressible Fluid ◽  
Friction Force ◽  
Viscous Incompressible Fluid ◽  
Peristaltic Transport ◽  
Two Dimensional ◽  
Peristaltic Motion ◽  
Long Wavelength ◽  
Permeable Walls

In the present investigation, problem of heat transfer has been studied during peristaltic motion of a viscous incompressible fluid for two-dimensional nonuniform channel with permeable walls under long wavelength and low Reynolds number approximation. Expressions for pressure, friction force, and temperature are obtained. The effects of different parameters on pressure, friction force, and temperature have been discussed through graphs.

Bifurcation Characteristics of Flows in Rectangular Sudden Expansion Channels

2005 ◽  
Author(s):  
Francine Battaglia ◽  
George Papadopoulos
Keyword(s):  
Reynolds Number ◽  
Laminar Flow ◽  
Critical Reynolds Number ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Expansion Ratio ◽  
Sudden Expansion ◽  
Two Dimensional ◽  
Effective Expansion ◽  
Three Dimensional Simulations

The effect of three-dimensionality on low Reynolds number flows past a symmetric sudden expansion in a channel was investigated. The geometric expansion ratio of in the current study was 2:1 and the aspect ratio was 6:1. Both experimental velocity measurements and two- and three-dimensional simulations for the flow along the centerplane of the rectangular duct are presented for Reynolds numbers in the range of 150 to 600. Comparison of the two-dimensional simulations with the experiments revealed that the simulations fail to capture completely the total expansion effect on the flow, which couples both geometric and hydrodynamic effects. To properly do so requires the definition of an effective expansion ratio, which is the ratio of the downstream and upstream hydraulic diameters and is therefore a function of both the expansion and aspect ratios. When the two-dimensional geometry was consistent with the effective expansion ratio, the new results agreed well with the three-dimensional simulations and the experiments. Furthermore, in the range of Reynolds numbers investigated, the laminar flow through the expansion underwent a symmetry-breaking bifurcation. The critical Reynolds number evaluated from the experiments and the simulations was compared to other values reported in the literature. Overall, side-wall proximity was found to enhance flow stability, helping to sustain laminar flow symmetry to higher Reynolds numbers in comparison to nominally two-dimensional double-expansion geometries. Lastly, and most importantly, when the logarithm of the critical Reynolds number from all these studies was plotted against the reciprocal of the effective expansion ratio, a linear trend emerged that uniquely captured the bifurcation dynamics of all symmetric double-sided planar expansions.

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